U.S. patent application number 13/549095 was filed with the patent office on 2014-01-16 for mems devices, packaged mems devices, and methods of manufacture thereof.
This patent application is currently assigned to TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD.. The applicant listed for this patent is Chun-Wen Cheng, Kai-Chih Liang. Invention is credited to Chun-Wen Cheng, Kai-Chih Liang.
Application Number | 20140015069 13/549095 |
Document ID | / |
Family ID | 49913270 |
Filed Date | 2014-01-16 |
United States Patent
Application |
20140015069 |
Kind Code |
A1 |
Liang; Kai-Chih ; et
al. |
January 16, 2014 |
MEMS Devices, Packaged MEMS Devices, and Methods of Manufacture
Thereof
Abstract
MEMS devices, packaged MEMS devices, and methods of manufacture
thereof are disclosed. In one embodiment, a microelectromechanical
system (MEMS) device includes a first MEMS functional structure and
a second MEMS functional structure. An interior region of the
second MEMS functional structure has a pressure that is different
than a pressure of an interior region of the first MEMS functional
structure.
Inventors: |
Liang; Kai-Chih; (Zhubei
City, TW) ; Cheng; Chun-Wen; (Zhubei City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Liang; Kai-Chih
Cheng; Chun-Wen |
Zhubei City
Zhubei City |
|
TW
TW |
|
|
Assignee: |
TAIWAN SEMICONDUCTOR MANUFACTURING
COMPANY, LTD.
Hsin-Chu
TW
|
Family ID: |
49913270 |
Appl. No.: |
13/549095 |
Filed: |
July 13, 2012 |
Current U.S.
Class: |
257/415 ;
257/E21.002; 257/E29.324; 438/51 |
Current CPC
Class: |
B81C 1/00285 20130101;
B81C 2203/0172 20130101; B81B 7/02 20130101; B81B 7/0038
20130101 |
Class at
Publication: |
257/415 ; 438/51;
257/E29.324; 257/E21.002 |
International
Class: |
H01L 29/84 20060101
H01L029/84; H01L 21/02 20060101 H01L021/02 |
Claims
1. A microelectromechanical system (MEMS) device, comprising: a
first MEMS functional structure having an interior region, the
interior region sealed by a first sealing ring; a shallow trench
underlying the first sealing ring; and a second MEMS functional
structure, wherein an interior region of the second MEMS functional
structure is sealed by a second sealing ring and has a pressure
that is different than a pressure of the interior region of the
first MEMS functional structure.
2. The MEMS device according to claim 1, wherein the first MEMS
functional structure and the second MEMS functional structure
comprise a type selected from the group consisting essentially of a
gyroscope, resonator, accelerometer, microphone, pressure sensor,
inertia sensor, actuator, and combinations thereof.
3. The MEMS device according to claim 1, further comprising a third
MEMS functional structure, wherein an interior region of the third
MEMS functional structure has a pressure that is different than the
pressure of the interior region of the first MEMS functional
structure or the pressure of the interior region of the second MEMS
functional structure.
4. The MEMS device according to claim 1, further comprising a third
MEMS functional structure, wherein an interior region of the third
MEMS functional structure has a pressure that is substantially the
same as the pressure of the interior region of the first MEMS
functional structure or the pressure of the interior region of the
second MEMS functional structure.
5. The MEMS device according to claim 1, further comprising a
plurality of third MEMS functional structures.
6. The MEMS device according to claim 1, wherein the first MEMS
functional structure or the second MEMS functional structure
comprises a sensor.
7. The MEMS device according to claim 1, further comprising an
encapsulating material disposed over the first MEMS functional
structure or the second MEMS functional structure.
8. A packaged device, including: a substrate; a
microelectromechanical system (MEMS) device coupled to the
substrate, wherein the MEMS device comprises a first MEMS
functional structure and a second MEMS functional structure,
wherein an interior region of the first MEMS functional structure
is sealed by a first sealing ring and has a first pressure, wherein
an interior region of the second MEMS functional structure is
sealed by a second sealing ring and has a second pressure, and
wherein the second pressure is different than the first pressure;
and at least one shallow trench underlying at least one of the
first sealing ring and the second sealing ring.
9.-10. (canceled)
11. The packaged device according to claim 8, further comprising an
encapsulating material disposed over the sealing material, the
first MEMS functional structure, or the second MEMS functional
structure.
12. The packaged device according to claim 8, wherein the substrate
comprises a first substrate, and wherein the MEMS device includes a
second substrate coupled to a third substrate.
13. The packaged device according to claim 12, wherein a moveable
element of the first MEMS functional structure or the second MEMS
functional structure is disposed between the second substrate and
third substrate.
14. The packaged device according to claim 8, wherein the substrate
comprises a cap wafer comprising a routing substrate or a
complementary metal oxide semiconductor (CMOS) wafer.
15. A method of manufacturing a microelectromechanical (MEMS)
device, the method comprising: forming the MEMS device, the MEMS
device including a first MEMS functional structure and a second
MEMS functional structure; forming a first sealing ring sealing an
interior of the first MEMS functional structure and a second
sealing ring sealing an interior of the second MEMS functional
structure; forming under at least one of the first sealing ring and
the second sealing ring, a shallow trench extending from outside at
least one of the first MEMS functional structure and the second
MEMS functional structure to an interior region of the at least one
of the first MEMS functional structure and the second MEMS
functional structure; attaching the MEMS device to a substrate;
creating a first pressure in an interior region of the first MEMS
functional structure; and creating a second pressure in an interior
region of the second MEMS functional structure, wherein the second
pressure is different than the first pressure in the MEMS device
after wafer level packaging of the MEMS device.
16. The method according to claim 15, wherein creating the first
pressure comprises applying a vacuum to the first MEMS functional
structure, or wherein creating the second pressure comprises
applying a vacuum to the second MEMS functional structure.
17. The method according to claim 15, further comprising applying a
sealing material on the first MEMS functional structure while
creating the first pressure, or applying a sealing material on the
second MEMS functional structure while creating the second
pressure.
18. The method according to claim 15, wherein the first MEMS
functional structure or the second MEMS functional structure
comprises a shallow trench disposed beneath a sealing ring, and
wherein the method comprises creating the first pressure or
creating the second pressure using the shallow trench beneath the
sealing ring.
19. The method according to claim 15, wherein creating the first
pressure in the interior region of the first MEMS functional
structure or creating the second pressure in the interior region of
the second MEMS functional structure comprises using a pump.
20. The method according to claim 15, further comprising attaching
a bonding ring to the substrate around and between the first MEMS
functional structure and the second MEMS functional structure.
Description
BACKGROUND
[0001] Microelectromechanical system (MEMS) devices comprise a
relatively new technology that combines semiconductors with very
small mechanical devices. MEMS devices are micro-machined sensors,
actuators, and other structures that are formed by the addition,
subtraction, modification, and patterning of materials using
techniques originally developed for the semiconductor
device/integrated circuit industry. MEMS devices are used in a
variety of applications, such as in sensors for motion controllers,
inkjet printers, airbags, microphones, and gyroscopes, as examples.
The applications that MEMS devices are used in continue to expand
and now also include applications such as mobile phones,
automobiles, global positioning systems (GPS), video games,
consumer electronics, automotive safety, and medical technology, as
examples.
[0002] One type of smaller packaging for MEMS devices that has been
developed is wafer level packaging (WLP). WLP involves packaging
MEMS devices in packages that typically include a redistribution
layer (RDL) that is used to fan out wiring for contact pads of the
MEMS devices, so that electrical contact can be made on a larger
pitch than contact pads of the MEMS devices and connections can be
made to other devices or to a board in an end application, for
example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] For a more complete understanding of the present disclosure,
and the advantages thereof, reference is now made to the following
descriptions taken in conjunction with the accompanying drawings,
in which:
[0004] FIGS. 1 through 12 are cross-sectional views illustrating a
method of manufacturing and packaging a MEMS device in accordance
with an embodiment;
[0005] FIG. 13 is a top view of the packaged MEMS device shown in
FIG. 12;
[0006] FIG. 14 is a top view of a packaged MEMS device in
accordance with an embodiment;
[0007] FIG. 15 is a more detailed view of a portion of the packaged
MEMS device shown in FIG. 14;
[0008] FIG. 16 is a graph illustrating various internal pressures
of MEMS functional structures of the MEMS device shown in FIG.
14;
[0009] FIG. 17 is a cross-sectional view illustrating a method of
controlling and establishing the various internal pressures of the
MEMS device using a pump in accordance with an embodiment; and
[0010] FIG. 18 is a flow chart showing a method of manufacturing a
MEMS device having different internal pressures in accordance with
an embodiment.
[0011] Corresponding numerals and symbols in the different figures
generally refer to corresponding parts unless otherwise indicated.
The figures are drawn to clearly illustrate the relevant aspects of
the embodiments and are not necessarily drawn to scale.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0012] The making and using of the embodiments of the present
disclosure are discussed in detail below. It should be appreciated,
however, that the present disclosure provides many applicable
inventive concepts that can be embodied in a wide variety of
specific contexts. The specific embodiments discussed are merely
illustrative of specific ways to make and use the disclosure, and
do not limit the scope of the disclosure.
[0013] Embodiments of the present disclosure are related to the
manufacturing and packaging of MEMS devices. Novel MEMS devices,
manufacturing methods, and packaged MEMS devices will be described
herein.
[0014] FIGS. 1 through 12 are cross-sectional views illustrating a
method of manufacturing and packaging a MEMS device 100 in
accordance with an embodiment. Referring first to FIG. 1, there is
shown a cross-sectional view of a MEMS functional structure 100a of
a MEMS device 100 at an initial stage of manufacturing in
accordance with an embodiment of the present disclosure. The MEMS
functional structure 100a includes a substrate 102. The substrate
102 may comprise silicon wafer, GaAs wafer, glass, or other
materials. The substrate 102 is also referred to herein as a first
substrate. An oxide 104a and 104b is formed on the front and back
side of the substrate 102 using an oxidation process. The oxide
104a and 104b comprises silicon dioxide having a thickness of about
2 .mu.m, or greater than 2 .mu.m to reduce parasitic feed-through
capacitance while operating MEMS devices, as examples, although
alternatively, the oxide 104a and 104b may comprise other materials
and dimensions.
[0015] The oxide 104b on the back side of the substrate 102 is
patterned using a lithography process, as shown in FIG. 2. The
oxide 104b can be patterned by depositing a layer of photoresist
(not shown) over the oxide 104b, exposing the layer of photoresist
to energy reflected from or transmitted through a lithography mask
(also not shown), developing the layer of photoresist, and then
removing the exposed or unexposed photoresist, depending on whether
the photoresist is positive or negative, for example. Portions of
the layer of photoresist are then ashed or etched away, and the
layer of photoresist is then used as an etch mask while portions of
the oxide 104b are etched away using an etch process. The patterns
in the oxide 104b comprise alignment marks or reference feature
patterns, e.g., dicing cut lines for subsequent integration
processes usage, that are used to align the substrate 102 during
subsequent various manufacturing processes, for example.
[0016] After the patterning of the oxide 104b, the substrate 102 is
inverted, as shown in FIG. 2. A stopper layer 106 comprising a
nitride having a thickness of about hundreds of nanometers, e.g.,
about 200 nm, is formed on the front side of the substrate 102, and
a dielectric film 108 comprising an oxide such as silicon dioxide
having a thickness of about 2 .mu.m, or greater than 2 .mu.m, is
formed over the stopper layer 106, also shown in FIG. 2. The
stopper layer 106 may comprise SiN and can be used for a subsequent
oxide release step, for example. Alternatively, the stopper layer
106 and the dielectric film 108 may comprise other materials and
dimensions.
[0017] Shallow leakage trenches 112 and patterns for anchors or
trenches 114 and bumps 110 are formed on the front side of the
substrate 102. The bump patterns 110 are formed in a top surface of
the dielectric film 108, and the shallow leakage trenches 112,
providing a path for vacuum pressure leak after WLP processes, are
formed through the dielectric film 108. The anchor patterns 114 are
formed only in the dielectric film 108. The shallow leakage
trenches 112 and patterns for anchors 114 and bumps 110 are formed
either using three lithography processes, e.g., using three
lithography masks and three etch processes, in some embodiments.
Alternatively, the shallow leakage trenches 112 and patterns for
anchors 114 and bumps 110 are formed in one lithography process,
and the final etch depth control in each specified locations 110,
112, and 114 are determined by pattern size features, e.g., by a
dry plasma etching loading effect wherein the larger the opening
size, the deeper the etched depth is. Alternatively, the shallow
trenches 112 and the patterns for the anchors 114 and bumps 110 can
be directly patterned.
[0018] Referring next to FIG. 4, a second substrate 116 is
provided. The second substrate 116 comprises similar materials
described for the first substrate 102 and in some embodiments
comprises silicon. The second substrate 116 is bonded using a wafer
bonding process to the front side of the first substrate 102. The
second substrate 116 can be bonded to the first substrate 102 using
fusion bonding, as an example. The second substrate 116 is thinned
using a grinding process, CMP process, dry plasma etch back
process, or combinations of such processes to control a final
second substrate 116 thickness to about 10 .mu.m to about 60 .mu.m
as an example. An oxide 118 comprising silicon dioxide having a
thickness of about 2 .mu.m is deposited on the substrate 116. The
oxide 118 may alternatively comprise other materials and
dimensions. The oxide 118 is used later for gap control of the MEMS
device 100 and the thickness is selected as needed for the MEMS
functional structure 100a. The oxide 118 and second substrate 116
are patterned, e.g., using a dry plasma reactive ion etch (RIE) and
a deep reactive ion etch (DRIE) process, as shown in FIG. 5,
forming patterns 120 for plugs.
[0019] Polysilicon or other type of semiconductive material is
formed over the oxide 118, filling the patterns 120 in the oxide
118 and second substrate 116. The polysilicon is planarized using a
chemical mechanical polishing (CMP) process and/or an etch process,
removing the polysilicon from over the top surface of the oxide 118
and leaving polysilcon plugs 122 formed in the dielectric film 108,
substrate 116, and oxide 119, as shown in FIG. 6. The polysilicon
plugs 122 at the edges in FIG. 6 comprise anchors for the MEMS
functional structure 100a, and the polysilicon plug 122 in the
center comprises a stop for a movable element of the MEMS
functional structure 100a, for example, in some embodiments.
[0020] A conductive material 124 is formed over the oxide 118 and
the top surface of the polysilicon plugs 122. The conductive
material 124 may comprise a metal, Ge, and/or a metal alloy that is
formed by sputtering in some embodiments. The conductive material
124 may have a thickness of about 0.5 .mu.m or greater, for
example. Alternatively, the conductive material 124 may comprise
other materials and dimensions, and may be formed by other methods.
The conductive material 124 is patterned using a lithography
process, leaving conductive material 124 disposed over the anchors
comprising the plugs 122 at the edges of the MEMS functional
structure 100a, as shown in FIG. 7.
[0021] The oxide 118 is etched back using an etch process, as shown
in FIG. 8. A portion of the oxide 118 remains on sidewalls of the
plugs 122 comprising the anchors. An oxide 126 is formed over the
substrate 116, conductive material 124, and the center plug 122, as
shown in FIG. 9. The oxide 126 may comprise silicon dioxide having
a thickness of about 1.0 .mu.m, although alternatively, the oxide
126 may comprise other materials and dimensions. The oxide 126 is
patterned for key MEMS functional structures, and the oxide 126 is
then used as an etch hard mask during an etch process for the
substrate 116, forming patterns 128 in the substrate 116.
[0022] A vaporized hydrofluoric (HF) acid etch process or other
type of etch process is used to remove the oxides 126 and 118,
dielectric film 108 and portions of oxide 104a, as shown in FIG.
10, forming the MEMS functional structure 100a. The HF etch process
is a releasing step that removes the sacrificial oxides 126 and
118, dielectric film 108 and portions of the oxide 104a, allowing
moveable elements (not shown) of the MEMS functional structure 100a
to have mechanical movement within an inner region cavity 154 of
the MEMS functional structure 100a. The HF etch process also
releases the shallow trenches 112.
[0023] Referring next to FIG. 11, a third substrate 130 is
provided. The third substrate 130 comprises a cap wafer which is
bonded to the conductive material 124 of the MEMS functional
structure 100a. The third substrate 130 comprises a routing
substrate or a complementary metal oxide semiconductor (CMOS)
wafer, as examples. The third substrate 130 includes a wafer 132
having an oxide 134a and 134b formed on the front side and back
side, respectively. The wafer 132 comprises a semiconductor
material, glass, or other material, and the oxide 134a and 134b
comprises silicon dioxide having a thickness of about 2 .mu.m, as
examples. Alternatively, the oxide 134a and 134b may comprise other
materials and dimensions.
[0024] A conductive material 136 is formed over the oxide 134b and
patterned. The conductive material 136 may comprise polysilicon, a
metal, or a metal alloy having a thickness of about 3 k.ANG., as an
example, although alternatively, the conductive material 136 may
comprise other materials and dimensions. The conductive material
136 is patterned using lithography, and an insulating material 138
is formed over conductive material 136. Insulating material 138
comprises about 1 .mu.m of silicon dioxide in some embodiments,
although alternatively, the insulating material 138 may comprise
other dimensions and materials. The insulating material 138 is
patterned, and a conductive material 140 is formed over the
patterned insulating material 138. The conductive material 140 may
comprise about 0.8 .mu.m of AlCu or an AlCu alloy to make ohmic
contact directly between an interface of two conductive layers in
some embodiments, although alternatively, the conductive material
140 may comprise other dimensions and materials. The conductive
material 140 is then patterned using a lithography process, as
shown in FIG. 11.
[0025] The MEMS functional structure 100a is then coupled to the
third substrate 130, forming a packaged MEMS device 150 using a
wafer level bonding technique (e.g., used in wafer level
packaging), as shown in FIG. 12. The MEMS functional structure 100a
will be well protected and sealed at a predetermined vacuum level
ranging from about 1 mbar to about 1 atm inside the close-up ring
142. The second substrate 116 is coupled to the third substrate
130, and portions of the first substrate 102 and the second
substrate 116 are diced to expose the patterned conductive material
140 comprising contact pads defined on the third substrate 130.
FIG. 13 shows a top of the packaged MEMS device 150 shown in FIG.
12. Conductive material 124 of the MEMS functional structure 100a
is coupled to the patterned conductive material 140 on the third
substrate 130 using a metal-to-metal bond, eutectic bond, or other
methods. Conductive material 124 comprises a eutectic material in
some embodiments, for example. The MEMS functional structures 100a
will be well protected inside the close-up ring 142. The conductive
material 140 on the left in FIGS. 12 and 13 comprises contact pads
for the packaged MEMS device 150. The region of the packaged MEMS
device 150 above the contact pads comprises an opening for
wire-bonds or a subsequent packaging level interface, for
example.
[0026] Only one MEMS functional structure 100a of a MEMS device 100
is shown in FIGS. 1 through 12; however, a plurality of MEMS
functional structures 100a are simultaneously formed on the first
and second substrates 102 and 116 for the MEMS device 100 in
accordance with embodiments, as shown in FIGS. 14 at 100a, 100b,
100c, and 100d, to be described further herein. A plurality of the
MEMS devices 100 including the MEMS functional structures 100a,
100b, 100c, and 100d are formed on the first and second substrates
102 and 116. Later in the process flow, after attaching the MEMS
device 100 to the third substrate 130 and applying one or more
pressures, to be described further herein, the MEMS devices 100 are
separated or singulated into packaged MEMS device 150 (see FIG.
12), e.g., by sawing the three bonded substrates 102, 116, and 130
along a scribe line.
[0027] After the third substrate 130 is coupled to the MEMS
functional structure 100a (and also at least one other MEMS
functional structure 100b, 100c, and 100d), pressure is created in
the interior region of the MEMS functional structures 100a, in
accordance with embodiments. The interior region comprises an inner
region cavity 154 that contains a moveable element of each of the
MEMS functional structures 100a in some embodiments, for example.
The inner region cavity 154 containing the moveable element is
disposed between the first substrate 102 and the second substrate
116. The amount of pressure applied is different for at least two
of the MEMS functional structures 100a, 100b, 100c, and 100d in
accordance with embodiments.
[0028] During the application of the pressure, a sealing material
148, shown in phantom in FIG. 12, is applied to the MEMS functional
structure 100a. As an example, the bonded substrate 130 and MEMS
functional structures 100a may be placed in a chamber, and a
pressure can be applied in the chamber. The pressure may be applied
by creating a vacuum inside the chamber to apply a vacuum to the
MEMS functional structure 100a, as an example. The sealing material
148 is then applied along edges of the MEMS functional structures
100a while the pressure is maintained in the chamber. The sealing
material 148 maintains the pressure inside the MEMS functional
structure 100a after the MEMS device 100 is removed from the
chamber. A hermetic vacuum seal is formed inside the MEMS
functional structure 100a in some embodiments. The sealing material
148 comprises a sealing ring, a sealing ring with shallow trench
patterns disposed beneath the sealing ring, a bonding ring, or a
sealing gel in some embodiments, for example. The sealing material
148 may comprise a thin film oxide, polyimide, epoxy, or an organic
gel having a thickness of about 10 .mu.m, as examples, although
alternatively, the sealing material 148 may comprise other
materials and dimensions. The sealing material 148 does not extend
into the inner region 154 containing the moveable element.
[0029] A different pressure may be created in interior region
cavities 154 of the various MEMS functional structures 100a, 100b,
100c, and 100d of the MEMS device 100, depending on the pressure
required for the particular MEMS functional structure 100a, 100b,
100c, and 100d. Some MEMS functional structures 100a, 100b, 100c,
and 100d may not require a particular pressure in some embodiments,
and a sealing material 148 may not be required.
[0030] An encapsulation material 152 may also be applied, or may
alternatively be applied (e.g., to the sealing material 148), while
the bonded substrate 130 and MEMS functional structures 100a, 100b,
100c, and 100d (e.g., over all of the MEMS functional structures of
the MEMS device 100) are in the chamber. The encapsulation material
152 may alternatively be applied after the bonded substrate 130 and
MEMS functional structures 100a, 100b, 100c, and 100d have been
removed from the chamber, in other embodiments. The encapsulating
material 152 is disposed over the sealing material 148, if
included, and over the MEMS functional structures 100a, 100b, 100c,
and 100d, as shown in phantom in FIG. 12. The encapsulating
material 152 may comprise glass or a CMOS packaging gel having a
thickness of about 1 mm, as examples, although alternatively, the
encapsulating material 152 may comprise other materials and
dimensions. The encapsulating material 152 protects the MEMS
functional structures 100a, 100b, 100c, and 100d in harsh
environments, such as moisture or shock, and also assists in
providing pressure control for the interior region cavities 154 of
the MEMS functional structures 100a, 100b, 100c, and 100d, for
example.
[0031] In some embodiments, one or more of the MEMS functional
structures 100a, 100b, 100c, and 100d may not include a sealing
material 148 and/or an encapsulating material 152.
[0032] FIG. 14 is a top view of a packaged MEMS device 150 in
accordance with an embodiment. The packaged MEMS device 150
includes a plurality of the MEMS functional structures 100a, 100b,
100c, and 100d. The MEMS functional structure 100a comprises a
gyroscope, and the MEMS functional structure 100b comprises a
resonator. The resonator may comprise a radio frequency (RF)
resonator in some embodiments; however, other types of resonators
may be included. The MEMS functional structure 100c comprises an
accelerometer, and the MEMS functional structure 100d may comprise
a pressure sensor or a microphone. Alternatively, the MEMS
functional structures 100a, 100b, 100c, and 100d may comprise other
types of micro-electro-mechanical systems. One or more of the MEMS
functional structures 100a, 100b, 100c, and 100d may comprise a
sensor in some embodiments. In other embodiments, one or more of
the MEMS functional structures 100a, 100b, 100c, and 100d may
comprise gyroscopes, resonators, accelerometers, microphones,
pressure sensors, inertia sensors, actuators, or combinations
thereof, as examples.
[0033] The shallow trenches 112 that make the pressure balanced
inside the bonding ring 142 and outside the bonding ring 142, e.g.,
at a pressure of about 1 atm are shown in phantom in FIG. 14. The
shallow trench 112 extends through at least one edge of the MEMS
functional structures 100a, 100b, 100c, and 100d and comprises an
opening for application of the pressure. The shallow trenches 112
are sealed after application of the pressure by the bonding ring
142 or other type of sealing material 148 used, for example. The
shallow trenches 112 may not be included in each MEMS functional
structure 100a, 100b, 100c, and 100d, e.g., if the MEMS functional
structures 100a, 100b, 100c, and 100d have openings through which
the pressure can be applied.
[0034] FIG. 15 is a more detailed view of a portion of the packaged
MEMS device 150 shown in FIG. 14. A more detailed view of the
shallow trench 112 and the sealing material comprising the bonding
ring 142 is shown. The shallow trench 112 comprises an air channel
in some embodiments, which can be designed as a substantially
straight line with a narrow gap of about 0.2 .mu.m, for example.
Alternatively, the shallow trench 112 can be a nozzle type of
trench from a top view or a meandering type of trench, to let air
or gas penetrate through the channel easily.
[0035] FIG. 16 is a graph illustrating various internal pressures
of the plurality of MEMS functional structures 100a, 100b, 100c,
and 100d of the packaged MEMS device 150 shown in FIG. 14, by
application. A range of pressures for the MEMS functional structure
100a comprising a gyroscope may range from about 0.001 to 0.7 bar.
A range of pressures for the MEMS functional structure 100b
comprising a resonator may range from about 0.001 to 0.01 bar. A
range of pressures for the MEMS functional structure 100c
comprising an accelerometer may comprise about 0.1 to 1 bar. A
pressure for the MEMS functional structure 100d comprising a
pressure sensor or microphone may comprise about 1 bar.
Alternatively, internal pressures in the inner region cavity 154 of
the plurality of MEMS functional structures 100a, 100b, 100c, and
100d of the packaged MEMS device 150 may comprise other values, in
accordance with embodiments of the present disclosure. Pressures
for the various MEMS functional structures 100a, 100b, 100c, and
100d may advantageously vary from about a millibar (mbar) level to
a bar level, so that about 3 orders of magnitude of pressure
difference is achieved within a single packaged MEMS device 150,
for example.
[0036] FIG. 17 is a cross-sectional view illustrating a method of
controlling and establishing the various internal pressures using a
pump 144 in accordance with an embodiment. The pump 144 is placed
proximate the packaged MEMS device 150, and pressure 146 is applied
by the pump 144 on the packaged MEMS device 150. While the pressure
146 is applied by the pump 144, the sealing material 148 is applied
to a particular packaged MEMS device 150 that requires that
pressure. The process is continued for different pressure levels
required by the various MEMS functional structures 100a, 100b,
100c, and 100d of the packaged MEMS device 150. The pump 144 may be
placed in the chamber that the packaged MEMS device 150 is being
processed in, and the pressure 146 may be varied and applied as
needed for each of the MEMS functional structures 100a, 100b, 100c,
and 100d, after which the sealing material 148 is applied, for
example. Each of the MEMS functional structures 100a, 100b, 100c,
and 100d is sequentially processed to apply the appropriate amount
of pressure 146 for the particular application of the MEMS
functional structures 100a, 100b, 100c, and 100d.
[0037] Some of the MEMS functional structures 100a, 100b, 100c, and
100d may not have pressure 146 applied, in some embodiments. These
MEMS functional structures 100a, 100b, 100c, and 100d are exposed
to the pressure 146 while other of the MEMS functional structures
100a, 100b, 100c, and 100d have pressure 146 applied and are sealed
with the sealing material 148. However, because a sealing material
148 is not applied to the MEMS functional structures 100a, 100b,
100c, and 100d not needing an internal pressure, when the pressure
146 is removed, the MEMS functional structures 100a, 100b, 100c,
and 100d do not retain an internal pressure in the inner region
cavity 154.
[0038] Only four MEMS functional structures 100a, 100b, 100c, and
100d are shown in FIG. 14. There may be five or more MEMS
functional structures 100a, 100b, 100c, and 100d formed on a single
MEMS device 100 or on a single packaged MEMS device 150 in
accordance with embodiments. Some of the MEMS functional structures
100a, 100b, 100c, and 100d may have the same pressure applied.
Alternatively, all of the MEMS functional structures 100a, 100b,
100c, and 100d may have different pressures applied, for example.
In accordance with an embodiment, at least two of the MEMS
functional structures 100a, 100b, 100c, and 100d have different
internal pressures; e.g., different pressures in the interior
region cavity 154.
[0039] FIG. 18 is a flow chart 160 showing a method of packaging a
MEMS device 100 including a plurality of MEMS functional structures
100a and 100b (see FIG. 14) having different internal pressures A
and B (see FIG. 16) in accordance with an embodiment. In step 162,
a MEMS device 100 is formed that includes a first MEMS functional
structure 100a and a second MEMS functional structure 100b. In step
164, the MEMS device 100 is attached to a substrate 130. In step
166, a first pressure A is created in an interior region (e.g., in
an interior region cavity 154) of the first MEMS functional
structure 100a. In step 168, a second pressure B is created in an
interior region of the second MEMS functional structure 100b. The
second pressure B is different than the first pressure A.
[0040] Embodiments of the present disclosure include methods of
forming MEMS devices 100, and also include MEMS devices 100 that
include the novel MEMS functional structures 100a, 100b, 100c, and
100d having different internal pressures. Embodiments of the
present disclosure also include packaged MEMS devices 150 that have
been packaged using the novel methods and MEMS devices 100
described herein.
[0041] The packaged MEMS devices 150 comprise wafer level packages
(WLP) that can be mounted to a circuit board, substrate, or other
mounting platform, and then electrically coupled to other devices,
such as integrated circuits, other MEMS devices, resistors,
transistors, capacitors, and other elements or modules, depending
on the end application. Wire bonds and/or solder can be connected
to the patterned conductive material 140 on the top surface of the
substrate 130 (e.g., on the left in FIGS. 12 and 13), for example.
Alternatively, the substrate 130 can include contacts on a bottom
surface thereof, and the contacts can be mounted on a mounting
platform in an end application using solder balls (not shown).
[0042] The manufacturing and packaging process flow illustrated and
described for FIGS. 1 through 12 are for illustrative purposes:
other MEMS device structures and methods may be used. Similarly,
the packaged MEMS device 150 shown in FIG. 14 showing the various
functions of the MEMS functional structures 100a, 100b, 100c, and
100d is for illustrative purposes: two or more MEMS functional
structures 100a, 100b, 100c, and 100d described herein may be
formed in a single packaged MEMS device 150 in accordance with
embodiments. The MEMS functional structures 100a, 100b, 100c, and
100d may have the same function and MEMS structure, or they may
have different functions and structures, as another example.
[0043] Advantages of embodiments of the disclosure include
providing novel packaged MEMS devices 150, MEMS devices 100, and
methods of fabrication thereof, wherein the various MEMS functional
structures 100a, 100b, 100c, and 100d have different internal
pressures, depending on the MEMS functional structure 100a, 100b,
100c, and 100d requirements. Multiple sensors comprising the MEMS
functional structures 100a, 100b, 100c, and 100d are integrated
with different internal pressures in a single packaged MEMS device
150. Combining multiple MEMS functional structures 100a, 100b,
100c, and 100d on a single chip or packaged MEMS device 150 allows
the overall chip size to be reduced and results in a reduced number
of process flow steps. The methods described herein comprise
die-level integration processes that reduce packaged die costs and
surface area requirements. The MEMS devices 100 comprise multiple
chambers that contain the MEMS functional structures 100a, 100b,
100c, and 100d, which each chamber having a controllable pressure
level. Different pressure levels are advantageously formed in a
single packaged MEMS device 150. The novel MEMS device 100
structures and designs are easily implementable in manufacturing
process and packaging flows.
[0044] All of the MEMS devices 100 required for a particular end
application can be combined in a single packaged MEMS device 150 in
some embodiments, for example, resulting in an area and cost
savings. The overall footprint of the final board the packaged MEMS
device 150 is mounted on can advantageously be reduced. The space
savings provided by embodiments of the present disclosure is
particularly advantageous in end applications such as consumer
electronics, which have a trend in technology development of
shrinkage targets, for example.
[0045] In accordance with one embodiment of the present disclosure,
a MEMS device includes a first MEMS functional structure and a
second MEMS functional structure. An interior region of the second
MEMS functional structure has a pressure that is different than a
pressure of an interior region of the first MEMS functional
structure.
[0046] In accordance with another embodiment, a packaged device
includes a substrate and a MEMS device coupled to the substrate.
The MEMS device comprises a first MEMS functional structure and a
second MEMS functional structure. An interior region of the first
MEMS functional structure has a first pressure, and an interior
region of the second MEMS functional structure has a second
pressure. The second pressure is different than the first
pressure.
[0047] In accordance with yet another embodiment, a method of
manufacturing a MEMS device includes forming the MEMS device, the
MEMS device including a first MEMS functional structure and a
second MEMS functional structure. The MEMS device is attached to a
substrate. A first pressure is created in an interior region of the
first MEMS functional structure. A second pressure is created in an
interior region of the second MEMS functional structure. The second
pressure is different than the first pressure in the MEMS device
after wafer level packaging of the MEMS device.
[0048] Although embodiments of the present disclosure and their
advantages have been described in detail, it should be understood
that various changes, substitutions and alterations can be made
herein without departing from the spirit and scope of the
disclosure as defined by the appended claims. For example, it will
be readily understood by those skilled in the art that many of the
features, functions, processes, and materials described herein may
be varied while remaining within the scope of the present
disclosure. Moreover, the scope of the present application is not
intended to be limited to the particular embodiments of the
process, machine, manufacture, composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present disclosure, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed, that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present disclosure. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps.
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